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Charging your EV in 16 seconds

Lithium-ion batteries are mainly used in EVs to store energy, but the recharge time is often criticised and is one of the main reasons for the slow adoption rate of electric vehicles around the world. A team of engineers wants to change this, using a graphene supercapacitor that stores almost as much as a Li-ion battery but charges in just 16 seconds.

According to Santhakumar Kannappan and his team from the Gwangju Institute of Science and Technology in Korea,, it is time to use graphene. The team has built high-performance supercapacitors out of graphene that store almost as much energy as a lithium-ion battery, can charge and discharge in seconds, and maintain 98% of their initial value after 10,000 cycles.

What is new in this supercapacitor?

The Korean engineers have used a highly porous form of graphene that has a very large internal surface area. They create this graphene by reducing graphene oxide particles with hydrazine in water agitated with ultrasound. The graphene powder is then packed into a coin-shaped cell, a pressure of 300kg/cm2 for five hours and dried at 140°C.

The resulting graphene electrode is highly porous. A single gram of this material has a surface area bigger than a basketball court. That’s important because it allows the electrode to accommodate much more electrolyte. And this ultimately determines the amount of charge the supercapacitor can hold.

Kannappan and the other engineers have measured the performance of their supercapacitor. According to their report, their supercapacitor can store energy at a density of more than 64 Wh/kg at a current density of 5 A/g. That is almost comparable with lithium-ion batteries, which have an energy density of between 100 and 200 Wh/kg.

The engineers say they can fully charge the supercapacitor in just 16 seconds and have repeated this some ten thousand times without a significant reduction in capacitance. “These values are the highest so far reported in the literature,” they say.